Structured Light 3D Measurement Module for Compact Real-Time Inspection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional Structured Light Illumination (SLI) systems for 3D surface measurement are computationally heavy and have large footprints, making them impractical for real-time measurements in small spaces, such as inside machinery or pipelines, due to the need for multiple dedicated projector units and complex electronic control systems.
Innovation Solution
The use of a compact system employing a fixed-pattern optic that projects a superimposed SLI pattern composed of dual-frequency sinusoids, allowing for simultaneous projection of multiple patterns and reducing the need for complex phase unwrapping algorithms, utilizing a dual-frequency Phase Multiplexing (DFPM) and Period Coded Phase Measuring (PCPM) patterns with Lookup Table (LUT)-based processing for real-time data decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple dedicated projector units are used to project SLI patterns, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple projector units into a single projector that projects a composite structured light pattern containing multiple SLI patterns simultaneously. This merging approach maintains the measurement precision of multiple projectors while reducing system complexity by eliminating the need for multiple separate projector units and their associated control systems.
Solution Approach 2:
The single projector unit is designed to perform multiple functions by projecting a composite pattern that includes multiple SLI patterns with different frequencies and phases. This multi-functional approach allows one projector to replace multiple dedicated projectors, reducing device complexity while maintaining measurement capabilities.
2Measurement precision
If multiple dedicated projector units are used to project SLI patterns, then measurement precision is improved, but the footprint increases
Solution Approach 1:
The patent merges multiple projector units into a single compact projector that projects a composite structured light pattern. This consolidation significantly reduces the physical footprint of the system while maintaining the measurement precision that would otherwise require multiple separate projector units.
3Measurement precision
If complex phase unwrapping algorithms are used for processing, then measurement precision is improved, but computational complexity increases
Solution Approach 1:
The patent applies preliminary phase unwrapping directly to the projected SLI patterns before they reach the object. By pre-processing the light patterns to contain unwrapped phase information, the system eliminates the need for complex post-processing algorithms, thereby reducing computational complexity while maintaining measurement precision.
4Measurement precision
If conventional SLI systems are used for real-time measurement, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent uses periodic SLI patterns with different frequencies that can be projected simultaneously and captured in a single frame. This periodic structure allows for real-time measurement by enabling the system to capture complete phase information in one shot rather than requiring multiple sequential measurements, thereby improving productivity while maintaining precision.
Solution Approach 2:
The system enables continuous real-time measurement by projecting composite SLI patterns that contain all necessary phase information simultaneously. This allows for uninterrupted measurement of moving objects or continuous production lines, maintaining measurement precision while significantly improving productivity through continuous operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables high-resolution, real-time 3D measurements in compact environments with reduced computational complexity and flexibility for various applications, including moving objects, by simplifying the measurement process and integrating multiple patterns into a single projector unit.
Implementation Method 1
a fixed-pattern optic that projects a superimposed SLI pattern composed of dual-frequency sinusoids
Implementation Method 2
a fixed-pattern optic that projects a superimposed SLI pattern composed of dual-frequency sinusoids
Implementation Method 3
measuring, with a camera (lens and processing unit) the image reflected off the surface-of-interest
Data Source
AI summary
A surface measurement module for 3-D triangulation-based image acquisition of a subject-under-inspection and under observation by at least one camera. The module having: (a) casing housing an optical system comprising a plurality of lens elements positioned between a fixed-pattern optic and a light source; (b) an output of said fixed-pattern optic comprising a multi-frequency pattern comprising a plurality of pixels representing at least a first and second superimposed sinusoid projected simultaneously, each of the sinusoids represented by the pixels having a unique temporal frequency and each of the pixels projected to satisfyInp=Ap+∑k=1KBkpcos(2πfkyp+2πknN)Eq.(1.1)(c) the subject-under-inspection and fixed-pattern optic in relative linear motion during projection onto the subject-under-inspection of the output of the fixed-pattern optic; and (d) plurality of images captured of this output during projection onto the subject-under-inspection are used for the image acquisition.